1. Field of Industrial Application
The present invention relates to a polyacetal resin composition excellent in friction and abrasion resistance properties by improving the compatibility, dispersibility and interfacial adhesion between resins, which is obtained by blending a polyacetal resin with a specific olefinic polymer, an alkylene oxide polymer having a primary or secondary amine group(s), an inorganic filler together with, further, a lubricant if required, and melting and kneading.
2. Prior Arts
Since polyacetal resins have a well-balanced mechanical properties and are excellent in, for example, friction resistance and abrasion resistance properties, chemical resistance, heat resistance and electric characteristics, they have been widely used in some fields such as automobiles and electrical and electronic appliances. However, the performances required in such fields are gradually escalating. As one example, there has been desired to further improve the sliding performances as well as general physical properties. Such sliding performances include the friction and abrasion resistance properties against inorganic filler-blended materials.
For example, high requirements for decreasing costs and weights increases such cases that inorganic filler-blended materials, which is obtained by blending inorganic fillers such as glass fibers, glass flakes, talc and mica with a resin such as ABS, PC/ABS and PBT/ABS, are used for chassis of CD-ROM or the like. Generally, gear parts and lever parts are slid against the metal boss caulked or formed in a sheet metal chassis so that the friction and abrasion resistance properties against metal materials have been important. However, since the boss and others are molded together with the chassis into one piece using such resin materials, the sliding performances against the resin-made boss or resin-made guide has become more important.
The sliding against materials for the resin-made chassis needs much better friction and abrasion resistance properties than those necessary for the conventional sliding against metal materials because of insufficient friction and abrasion resistance properties inherent to ABS resin, as a partner material, and the effects of surface roughness caused by blended inorganic fillers. Thus, the improvement of such properties has been required.
In general, addition of a fluororesin or a polyolefinic resin, or addition of a lubricant such as fatty acids, fatty acid esters, silicone oils or various mineral oils, to polyacetal resins is effected for the purpose of the improvement of the sliding performances.
The addition of a fluororesin or a polyolefinic resin improves the sliding performances to a certain extent. However, since these resins other than the polyacetal resins exhibit poor compatibility with the polyacetal resins, the resultant resin compositions have unsatisfactory sliding performances under a high surface pressure, and they have poor abrasion resistance properties in the sliding against inorganic filler-blended materials. Further, there are problems in that they are liable to cause peeling on the surfaces of molded articles or to form a deposition on a mold.
While, the addition of a lubricant has various disadvantages such as the trouble of the processing in extrusion or molding, or the bleeding during using. Moreover, when used together with the above-mentioned resins other than the polyacetal resins, the lubricant inhibits the compatibility between these resins and the polyacetal resins and greatly deteriorates the abrasion resistance properties. For such problems, materials with these properties improved have been desired.